Acrylic tooth-filling composition containing boric acid-releasing compound

ABSTRACT

A tooth-filling composition non-toxic to tooth pulp comprising an acrylic-based filling composition containing boric acid or a compound of boron, such as tributyl borate, that liberates boric acid.

United States Patent [191 Gross 5] Nov. 5, 1974 1 1 ACRYLICTOOTH-FILLING COMPOSITION CONTAINING BORIC ACID-RELEASING COMPOUND [75]Inventor: Albert Gross, Frankfurt/Main,

Germany [73] Assignee: Kulzer & Co., GmbH, Bad

Homburg, Germany [22] Filed: Jan. 4, 1972 [21] App1.No.: 215,406

Related US. Application Data [63] Continuation of Ser. No. 56,646, July20, 1970, abandoned, and a continuation-in-part of Ser. No. 751,714,Aug. 12, 1968, abandoned.

[52] US. Cl 424/81, 32/15, 260/893,

' 260/895 R, 260/895 A, 424/148, 424/185 [51] Int. Cl A6lk 5/00 [58]Field of Search 106/35; 32/15; 260/893,

[56] References Cited UNITED STATES PATENTS 2,887,199 3/1959 Taub 106/35X 3,449,293 6/1969 Burzynski et a1. 260/893 UX 3,452,437 7/1969 Chang32/15 3,531,282 7 9/1970 Miller et a1. 204/159.23 X FOREIGN PATENTS ORAPPLICATIONS 14,318 8/1967 Japan 106/35 OTHER PUBLICATIONS PrimaryExaminerAllan Lieberman Attorney, Agent, or Firm-Burgess, Dinklage &Sprung [57] ABSTRACT A tooth-filling composition non-toxic to tooth pulpcomprising an acrylic-based filling composition containing boric acid ora compound of boron, such as tributyl borate, that liberates boric acid.

3 Claims, No Drawings RELATED APPLICATION This application is acontinuation of application Ser.

' No. 56, 646 filed July 20, 1970 and now abandoned.

Said application Ser. No. 56, 646 is a continuation -in -part of ToothPulp-Protecting Agent, Ser. No. 751, 7l4 filed Aug. 12, 1968 andabandoned August 11, I970.

PREAMBLE It has been known to use synthetic plastic materials forfilling tooth cavities, in the form of mixtures of polymers in powderform and monomeric liquids, which contain various types of additives, inparticular catalysts and/or accelerators for rapid curing at lowtemperatures. These filling materials have become widely used and haveproved generally satisfactory because of their desirable properties, butdo, however, frequently have disadvantages When not expertly used,damage of the tooth pulp may occur during the introduction of theuncured mixtures into the cavity and during the curing of the mixtures.Such irritation of the pulp, which starts with damage to theodontoblasts, may

cause death of the pulp. This irritation occurs primarily because anineffective sub-filling is used, which fails to keep the toxic monomericliquid out of contact with the viable pulp. Thus, with incorrect orinexpert subfilling the possibility is always present that the monomericliquid will diffuse, together with the sometimes also toxic catalystconstituents, through the layer of dentine covering the pulp and lead todamage or death of the pulp, either immediately or maybe after thefilling has cured.

This damage of the living tooth texture isbelieved not to be the resultof acidity, as occurs with other tooth filling materials, but probablyis the result of a protein precipitating effect by the stronglyfatdissolving monomer in the polymerizable liquid. Since the developmentof synthetic fillings in the dental field, there have been manyexperiments to protect the pulp from damage by the monomer liquid. It isknown to cover the cavity with a synthetic film prior to inserting thefilling material, which film is intended to prevent the monomer liquidfrom diffusing through into the living tooth pulp. However, theseso-called cavity varnishes have not been able to give effectiveprotection of the pulp, possibly because of the organic solventsintroduced during application of these synthetic films causing the sametexture damage also observed without the application of such a film.

, BIBLIOGRAPHY Acrylic-based tooth restorations have been used for sometime:

The Science of Dental Materials; Skinner and Phillips, W. B. SaundersCompany, Philadelphia, Fifth Edition, page 200 et seq., Chapter 13,Tooth Restorations with Acrylic Resins Clinical tests have shown thatfast hardening acrylicbased filling materials show statistically a pulpnecrosis rate greater than 4 percent:

1. Auto-polymerizing Resin Fillings, Coy, Bear and Kreshover, Journal ofthe American Dental Association, Volume 44, No. 3, March 1952, page 2552. Spreter von Kreudenstein Deutsche Zahnaerztliche Zeitschrift, 10,(1955), page 1619 3. Pulp Reactions to Restorative Materials Stanley,Swerdlow and Buonocore, Journal of the American Dental Association,Volume (1967) Some results of the case of filling material according tothis invention are given in:

l. Fischer, Grosz and Masuhara Deutsche Zahnaerztliche Zeitschrift, 23(1968), page 209 et seq.

2. Fischer, Knolle and Tan Das Deutsche Zahnaerzteblatt, 23 (1969), page251 et seq.

THIS INVENTION It has now been found that this type of damage of thepulp can be prevented by using boric acid or, under the fillingconditions compounds supplying boric acid, when working with thesynthetic fillings.

This invention consists of the use of boric acid (or under the fillingconditions of boron compounds supplying boric acid) in the applicationof known synthetic filling materials, particularly acrylic ones, whichconsist of a pulverulent polymer and a monomer liquid and containcatalysts and/or accelerators which provide for the fast hardening ofthe mixture at low temperatures. As is known, these mixtures of polymerpowder and monomer liquid are usually based on compounds of the acrylicacidand methacrylic acid series, especially on the acrylic acidandmethacrylic acid esters, homopolymers as well as copolymers being used.The monomer liquid does not have to be a single monomer, but may be amixture of different monomers. But such monomer liquids are toxic to thetooth pulp, as are the numerous compounds that may be used as catalystsand accelerators. This has been known in the dental field for a longtime, i.e., that such materials undesirably affect the pulp.

The boron compounds are preferably used in amounts of 0.01 to 5 percentby weight, advantageously 0.05 to 3 percent by weight, and in particular0.1 to lpercent by weight, based on the liquid constituents of theagent.

As well as boric acid itself, boron compounds, in particular borates,for example tributyl borate or trioctyl borate, have been proved to beeffective boron compounds for protecting the pulp. These effective boroncompounds can be used either directly in a suitable liquid, for exampledissolved in water or an organic solvent, or can be dissolved in amonomeric polymerisable liquid for brushing out the tooth cavity beforeinserting the filling. They can be and preferably are added to theEXAMPLES Examples 1 and 2 A plastic mixture suitable for the filling oftooth cavities consisted of a fill composition containing pulverulentmethyl methacrylate polymer or copolymer, which was mixed with monomericmethyl methacrylate to form a pasty mixture and was cured under theinfluence of a Redox System as known per se after introduction into atooth cavity to form a filling. The monomeric liquid contained 0.1percent free boric acid. A filling material which was of similarcomposition but which contained percent of tributyl borate in themonomeric liquid also formed a satisfactory filling. With bothcompositions it was impossible to determine any damage to the pulp bythe plastic filling or by the constituents thereof, which are toxic inthe uncured state.

Examples 3, 4 and 5 These filling materials are prepared in accordancewith known methods whereby the pulverulent polymers and monomericliquids are mixed in a suitable ratio and are brought into the toothcavity wherein the mixture polymerizes or hardens into the filling in afew minutes under the influence of the catalysts and accelerators atmouth temperature. In general, there are mixed about two parts powderwith one part liquid; however, these quantities can vary, depending onthe portion of the filler.

3. Powder: A pearl polymer of 95 percent methacrylic acid methylesterand 5 percent butylphthalylbutylglycolate (Santicizer B-l6-MonsantoChemical), particle size 50 p. is ground with l percentdibenzoylperoxide with small additions of inorganic pigments to give themixture a tooth-like color.

Liquid: 92 percent methacrylic acid methyl ester, 4.5 percentglycol-dimethacrylate, 0.5 percent dimethyl-p-toluidine, 3 percenttributylborate.

4. Powder: This powder corresponds to that of Exampie 3, but contains inaddition 0.6 percent di-p- 4 toluene-sulfonylmethylmethylamine.

Liquid: 99 parts by weight methacrylic acid methylester, 0.5 parts byweight B-phenylethyldimethylcarbethoxymethyl-ammoniumchloride, 0.03parts by weight copperacetylacetonate. Directly prior to mixing, thereare dissolved in the liquid 3 parts by weight of tri-n-butyl-boron.

5. Powder: First, percent quartz flower having a particle size of 50 uare mixed with 25 percent of a copolymer of percent methacrylic acidmethylester and 5 percent butylacrylate in pearl form having a particlesize of 50 ;1.. To this mixture there is added, besides pigments, 1percent dibenzoylperoxide and 2 percent boric acid. The liquid componentcorresponds to that of Example 3.

I claim:

1. In a tooth-filling composition comprising a monomeric acrylicpolymerizable liquid toxic to tooth pulp and suited for use in dentalfilling materials, and a Redox System curing agent, the improvementwhich comprises adding a boric acid alkyl ester, said compound beingdissolved in said monomeric acrylic polymerizable liquid in a non toxicamount sufficient to protect the tooth pulp of a prepared tooth whenusing said toothfilling composition therein.

2. The tooth-filling composition of claim 1 wherein said ester ispresent in a quantity in the range of 0.01 to 5 weight percent,calculated on the polymerizable liquid of said composition.

3. The tooth-filling composition of claim 2- wherein said estersupplying boric acid is selected from the group consisting of tri-butylborate and tri-octyl borate. l =l Attesting'0fficer 2233; 0mm) SI'A'I'ESPATENT omen CERTIFICATE OF CORRECTION P tent No. 3,846,542 Q DatedNovember 5, 1974 Inventofls) I ALBERT GROSS It is certified that errorappears- 1n the aboye-identified patent and that said Letters Patent arehereby corrected as shown below:

Page 1 of the pa tenI; deed, under'iter n'[21] Insert the following:

-- [30] FOREIGN APPLICATION PRIORITY DATA I August 18, 1967 Germany...... 1 3134 IV/a30h Col. 2, line 58, cancel "hydrolysiscan" andsubstitute hydrolysis can Signed and sealed this 1st day of April 1975.

(SEAL) Attest:

C. MARSHALL DANN Commissioner of Patents and Trademarks RUTH C. I'IASOII

1. IN A TOOTH-FILLING COMPOSITION COMPRISING A MONOMERIC ACRYLICPOLYMERIZABLE LIQUID TOXIC TO TOOTH PULP AND SUITED FOR USE IN DENTALFILLING MATERIALS, AND A REDOX SYSTEM CURING AGENT, THE IMPROVEMENTWHICH COMPRISES ADDING A BORIC ACID ALKYL ESTER, SAID COMPOUND BEINGDISSOLVED IN SAID MONOMERIC ACRYLIC POLYMERIZABLE LIQUID IN A NON TOXICAMOUNT SUFFICIENT TO PROTECT THE TOOTH PULP OF A PREPARED TOOTH WHENUSING SAID TOOTHFILLING COMPOSITION THEREIN.
 2. The tooth-fillingcomposition of claim 1 wherein said ester is present in a quantity inthe range of 0.01 to 5 weight percent, calculated on the polymerizableliquid of said composition.
 3. The tooth-filling composition of claim 2wherein said ester supplying boric acid is selected from the groupconsisting of tri-butyl borate and tri-octyl borate.